A NATION CHALLENGED: DISLOCATION; Learning to Navigate Where the Invisible Clues Have Changed

Past the turnstiles at 42nd Street, just when everyone else wants to hit top speed, Eddie Montanez throttles himself down a notch. Still moving, yes, but slower, more deliberately. Rushing is for people with eyes that still work, and for those who do not have to cut new paths across the city because their old routes were ripped asunder on Sept. 11.

For Mr. Montanez, 40, blind from age 13, the subway beneath the Port Authority Bus Terminal is fresh terrain. He used to come to work on the PATH train to the World Trade Center. Now he must tune his face, his ears, his skin to the currents of the crowds at 42nd Street, while he also screens the pinging MetroCards, the tumble of metal arms in the turnstiles, the mutters of people ordered to Please Swipe Again.

He tries to listen. He wants to be heard. So in his hand, Mr. Montanez says, he holds his cane, a few ounces of fiberglass and aluminum shaped into a long, skinny rod. ''I hit the cane harder, so people notice,'' Mr. Montanez explains. ''Sighted people, you have to watch out for them. People are moving so fast.''

The lost streets near the trade center had been rich with invisible clues about where things stood, how people moved, when traffic surged. The thwack-thwack pulse of a revolving door released wedges of sound and air; that was the entrance to a Borders bookstore near the corner of Church and Vesey.

Down the block, a door to a Krispy Kreme shop pumped its own notes onto the street. The Rite Aid on Church Street had a different odor than the Duane Reade a few blocks away. An exhaust fan above a Greek restaurant marked a spot on Church.

Suddenly, these were gone, or unreachable. For blind people with some light perception, small streets that were once dim, in permanent shadow, now bounce with sunlight for the first time in more than 30 years.

To learn new clues, scores of people who are blind or who have limited vision have spent hundreds of hours learning how to navigate the rearranged city.

''People had incredibly detailed maps of New York City in their heads, and this just wrecked them,'' said Nicole F. Feist, a mobility instructor with Visions, a nonprofit organization on Greenwich Street that got a $37,000 grant from the September 11th Fund to help blind people manage the changed world. ''This is the best city in the country for the blind. It's set up on a grid, set up for pedestrians. There's tons of public transportation.''

Subways were rerouted. Buses did not stop in the same place. Mr. Montanez works on a Web site for the Associated Blind, on William Street, where the utility cables run along the streets and sidewalk, instead of underground.

Another mobility instructor, Annie Presley, pointed out that a route that worked in the morning might be gone by lunchtime. ''It's not just the World Trade Center -- it's the uncertainty,'' she said. ''When the plane crashed in Rockaway, the bridges were closed again.''

The blind had long been told to steer clear of subway platforms that are islands between two tracks, said Annalyn Courtney Barbier, an instructor who helped Mr. Montanez. Because Mr. Montanez lost his PATH stop at the trade center, he often uses Broadway-Nassau, a station that includes an island platform and other vexations for those who can see and for those who cannot.

Long before the catastrophe, Mr. Montanez's cane served as an antenna that sent and received messages. Now it connects him to a drastically changed city.

A few days before the trade center attack, Mr. Montanez returned from Africa, where he had climbed Kilimanjaro. On the morning of the 11th, his office rattled when the first airplane struck. He thought a piece of machinery had been dropped somewhere, so he went down to William Street to investigate. ''I had never used the stairs before, didn't know where the door led to,'' he said.

A building engineer snapped a picture of him in the street, holding a mask, a water bottle and his cane. He walked for miles that day, the cane previewing every step across the stunned streets.

As for his old commuting route, that lost journey still has vivid life in his memory. ''I would arrive by PATH in the trade center,'' said Mr. Montanez, who lives in Hoboken, N.J. ''You would listen if the doors open in front of or behind you. The trick was to find escalators closest to you. To do that, you listen to people walking. Follow that. Make a right. Several steps, then the next right.

''I would be hearing a lot of people walking, then I'd hear the turnstiles. I think there was a bar to the left; there'd be no noise in the morning, but at night, on the way home, there's always music and people talking.

''Then I would hear wide-open space. Go up the stairs, not the escalator.''

Outside, he recalled: ''I avoid the cafe on the left, because tables were set up on the sidewalk. There were planters on the street. I would start trailing people, so I'd be on the corner of Church Street.''

In his vanished streetscape, two of the tallest buildings in the world are scarcely a presence. ''On that corner, there was always a guy -- always this homeless man,'' Mr. Montanez said. ''One time I didn't see him. He was in the hospital, or jail. He always would say, no matter how many times I told him not to yell across to me, 'It's O.K. now.' Once in a while, I gave him a dollar. I hope he made it.

''Make a right, then a left. I would continue walking. There was a combination of very rapid shoe sounds, people walking. A lot of carts of coffee, people buying doughnuts. There was a fruit stand, there, too. A lot of commotion. People selling. Stopping to buy.

''It's kind of sad.''

Articles in this series are reporting on workaday objects that resonate in unusual ways in the aftermath of Sept. 11.

Earlier articles are

available on the Web: nytimes.com/metro.

Correction: February 22, 2002, Friday A picture caption yesterday about Eddie Montanez, who is blind and was shown walking downtown on Sept. 11 after the attack, misidentified the location. It was John Street; William Street intersected it nearby.